EP2985045B1 - Method for adjusting a blood flow in a dialysis device and dialysis device - Google Patents

Description

The present invention relates to an extracorporeal blood treatment machine, preferably a dialysis machine, which allows blood flow to be adjusted. The extracorporeal blood treatment / cleaning machine, preferably dialysis machine, has a control device or control unit for adjusting the blood flow.

For extracorporeal blood treatment / blood purification, such as dialysis, the adjustment of blood flow (Qb) is of great importance for the treatment efficiency. For example, dialysis patients have an artificial puncture site or artificial access to the intracorporeal blood vessel system, which may consist of either a shunt (a vein-artery connection) or a central venous catheter. At this puncture site / vascular access, the blood for dialysis treatment is removed from the patient's body. Blood flow is typically targeted as high as possible, as higher blood flow is generally associated with greater cleansing performance, thereby providing better detoxification performance for the therapy and / or reducing treatment time.

oder in Prozent angegeben werden.During a dialysis treatment complications or certain unwanted phenomena may occur. Some lead to the assumption that a higher cleaning performance is no longer valid for a higher blood flow. An example of this is the occurrence of a so-called recirculation or local shunt recirculation. The recirculation or shunt recirculation (R) is defined as the ratio of the flows of recirculated blood (Qr) and blood pump rate or whole blood flow (Qb). Accordingly, recirculated blood is that blood which has already been purified and originates from the venous needle (blood return line) and which, together with still unpure patient blood, is conveyed (recirculated) directly back into the arterial needle (blood supply line). The recirculation or shunt recirculation (R) can be used as a ratio $$\mathrm{R}=\mathrm{qr}/\mathrm{Qb}$$

or in percent.

The medically indicated blood flow is u. a. depending on the state of the patient access or shunt. Thus, the attending physician is faced with the task of setting the blood flow in the extracorporeal blood treatment on the one hand as high as possible in order to achieve the maximum cleaning performance for a therapy as possible, but on the other hand not to set the blood flow too high to risk any recirculation or the Keep recirculation as small as possible.

Methods and machines for extracorporeal blood treatment / purification, such as dialysis, are known in the art.

US 5,863,421 A discloses an extracorporeal blood treatment machine in which blood flow and blood pressure values can be detected and controlled.

In the WO 2007/140993 a device for controlling an extracorporeal blood treatment machine is described. In this blood treatment machine, at least one predetermined flow rate of a group of flow rates comprising blood flow rate Qb, dialyzing fluid rate Qd, ultrafiltrate Qf and substituate Qs is at least one of the other flow rates from the group of flow rates including blood flow rate Qb, dialyzing fluid rate Qd, ultrafiltrate Qf and substituate rate Qs alone calculated on the basis of a predetermined dependence of the clearance K or dialysance D on the flow rates at which the given clearance K or dialysance D is maintained.

In the US 3,882,861 is a dialysis machine described, with the help of which the blood flow is adjusted pressure controlled. The blood flow is controlled by an electrical pulse sequence in which the respective pulse duration corresponds to changes in the negative pressure with changes in the blood flow. A disadvantage of this solution, however, is that the proposed machine is technically complex and therefore expensive. In addition, it has been found that such a pressure-controlled machine can not necessarily guarantee that the cleaning performance of the treatment is optimal.

In the EP 0 711 182 B1 is described a system for achieving the highest possible clearance value relative to the total patient body. The system has one A device for setting a parameter of dialysis efficiency, means for detecting a metabolic concentration, means for determining a metabolic profile as a function of the parameter change and means for comparing the measured metabolic concentration values to determine an optimal parameter with which Achieve maximum metabolic concentration.

A disadvantage of this prior art, however, is that the determination of the urea concentration in the outflow is used to obtain a statement in which blood flow is the dialysis fluid-side toxin concentration (urea concentration here) maximum. This measurement requires the setting of different blood flows. The measurement can be made after blood flow change only after reaching a stable value, i. after completion of the balancing process within the extracorporeal blood line system of the machine, take place dialysis fluid side. However, as the patient continues to be dialyzed during the measurements, it is doubtful that the correct blood flow can be determined at all, since the measurement times would have to be very high / long. The device and method are therefore not necessarily suitable for quickly determining the blood flow at which (substantially) maximum toxin removal is possible.

In the EP 1 083 948 B1 is a method for determining the concentration of waste products, ie filter-uremic toxins, described in the dialysis fluid during a dialysis treatment based on transmission spectroscopy. The measurement is performed spectrophotometrically, and the measurement result is multiplied by the flow rate from the dialyzer to determine the content of the substance (s) in the output dialysis fluid.

This makes it possible to measure the absorbance of a substance mixture which exists on the dialysis fluid side. From the data, however, no conclusion is drawn on the blood flow.

Finally, from the WO 2013/167264 a method and a device for extracorporeal blood treatment known, whereby an optimization of a predetermined blood flow rate in terms of maximizing the exchange performance of a dialyzer achieved shall be. For this purpose, the device and the method according to this prior art provide for the determination of at least one, but preferably of a plurality of parameters characteristic of the extracorporeal blood treatment, wherein a specific blood flow rate is determined in each case depending on the one or preferably one of the several characteristic parameters ,

Then, a blood flow rate is selected from a plurality of blood flow rates, which have been determined on the basis of the characteristic parameters, which is then specified for the current treatment. The selection of a blood flow rate is made using a (selection) algorithm implemented in a device-internal software / hardware. The algorithm allows automatic selection of a blood flow rate.

In view of this known state of the art, the object of the invention is to provide an extracorporeal blood treatment / cleaning machine, preferably a dialysis machine, with which an optimum blood flow (for a substantially maximum cleaning performance) can be set during a dialysis treatment. One goal is to be able to adjust the blood flow so that a recirculation is reduced or avoided, for example, in a patient shunt. Another goal is to make the process as simple as possible.

The object is achieved by an extracorporeal blood treatment machine (blood purification machine or dialysis machine) according to claim 1. Embodiments of the present invention are the subject of the dependent claims.

The invention is based in summary on the general process according to which the blood flow through the dialyzer is preferably linearly increased at a predetermined rate (ie within a certain (process) time t from a predetermined start value to a predetermined target value) during which it is continuous or timed by means of suitable sensors, the current venous and / or arterial pressure in the extracorporeal blood circulation as well as dialysis-side features / properties (in particular the current degree or amount of uremic toxins) are measured in a spent cleaning fluid (dialysis fluid). From these concrete measured values can then be for the current treatment (Individually) determining the most advantageous blood flow, preferably by comparing the acquired measured values with preset or already implemented (standardized) nominal values.

In this case, the detection / detection in particular of said dialysis-side features / properties with a dead time .DELTA.t (actually occurring delay time between the rate change made and the measurable at the sensors result thereof), which essentially consists of the distance between the dialyzer and sensor in the tube longitudinal direction and the (average) flow velocity of the cleaning liquid results. This dead time Δt will be included in the determination routine to make the final decision regarding the optimal blood flow adjustment.

1. a) Vorgeben eines Blutflusszielwertes, Qb_ziel, vorzugsweise über eine Kommunikationseinrichtung,
2. b) Verändern eines (vorgegebenen/vorgebbaren) anfänglichen Blutflusses, Qb_start (unterschiedlich zu Qb_ziel), mit einer vorgegebenen/vorgebbaren Blutflussänderungsrate und damit über eine vorbestimmte maximale Blutflussveränderungszeit in Richtung hin zum Blutflusszielwert, Qb_ziel beispielsweise durch eine Blutpumpen/Steuereinheit,
3. c) Vergleichen eines gemessenen aktuellen venösen Drucks PV, mit einem (vorgegebenen oder ausgewählten) venösen Druckschwellenwert; eines gemessenen aktuellen arteriellen Drucks PA, mit einem (vorgegebenen oder ausgewählten) arteriellen Druckschwellenwert; und eines gemessenen aktuellen Blutflusses Qb, mit dem Blutflusszielwert, Qb_ziel durch eine Vergleichereinheit,
4. d) Erfassen wenigstens eines aktuellen Dialysierflüssigkeitsparameters/-merkmals/- eigenschaft (Grad/Menge an in einer verbrauchten Dialysierflüssigkeit enthaltenen urämischen Toxinen z.B. über UV-Absorbtion/Absorbanz) mit einer Zeitverzögerung/Totzeit Δt bezüglich des Zeitpunkts des zugehörigen gemessenen Blutflusses (in Abhängigkeit von der Strömungsgeschwindigkeit der Dialysierflüssigkeit sowie des Strömungsabstands der Erfassungsstelle zum Dialysator) durch eine Erfassungseinrichtung und Ermitteln durch eine Ermittlungseinrichtung, ob der erfasste aktuelle Dialysierflüssigkeitsparameter einen Dialysierflüssigkeit-Parameterschwellenwert annähert/erreicht (Ermittlung des Auftretens eines Parameterextrems),
5. e) Abspeichern eines Blutflussoptimalwertes, Qb_optimum in einem Blutflussoptimalwertspeicher, in Abhängigkeit von jenem Blutfluss oder jener Blutflussrate, bei dem/der in Schritt d) der Dialysierflüssigkeit-Parameterschwellenwert (Parameterextrem) tatsächlich erreicht worden ist, oder bei dem in Schritt c) der venöse Druckschwellenwert PV bzw. der arterielle Druckschwellenwert PA erreicht worden ist und in Schritt d) der Dialysierflüssigkeit-Parameterschwellenwert noch nicht erreicht worden ist, wobei der Schritt d) um eine vorbestimmte Wartezeit tx ab Erreichen des venösen Druckschwellenwerts PV bzw. des arteriellen Druckschwellenwerts PA fortgeführt wird ,
6. f) Rückspringen zu Schritt b) vorzugsweise durch eine Rücksprungeinrichtung andernfalls.

For setting a blood flow for a substantially optimal cleaning performance, the following steps can be carried out in the extracorporeal blood treatment / cleaning machine, preferably dialysis machine:

1. a) prescribing a blood flow target value, Qb_ziel, preferably via a communication device,
2. b) changing a (predetermined / predefinable) initial blood flow, Qb_start (different from Qb_ziel), with a predetermined / predeterminable blood flow rate and thus over a predetermined maximum blood flow change time towards the blood flow target, Qb_ziel for example by a blood pump / control unit,
3. c) comparing a measured current venous pressure PV with a venous pressure threshold (predetermined or selected); a measured current arterial pressure PA, with a (predetermined or selected) arterial pressure threshold; and a measured current blood flow Qb, with the blood flow target value, Qb_ziel by a comparator unit,
4. d) detecting at least one current dialysing fluid parameter / characteristic / property (degree / amount of uremic toxins contained in a spent dialysis fluid, eg via UV absorption / absorbance) with a time delay / dead time Δt with respect to the time of the associated measured blood flow (as a function of the flow rate of the dialysis fluid and the flow distance of the detection point to Dialyzer) by a detection device and determining by a determination device whether the detected current dialysis fluid parameter approaches / reaches a dialysis fluid parameter threshold (determination of the occurrence of a parameter extremum),
5. e) storing a blood flow optimal value, Qb_optimum in a blood flow optimizing memory, depending on that blood flow or blood flow rate at which the dialysis fluid parameter threshold (parameter extender) has actually been reached in step d), or the venous pressure threshold in step c) PV or the arterial pressure threshold PA has been reached and in step d) the dialysis fluid parameter threshold has not yet been reached, wherein step d) is continued for a predetermined waiting time tx from reaching the venous pressure threshold PV or the arterial pressure threshold PA,
6. f) returning to step b), preferably by a return device otherwise.

Depending on the distance of the detection point to the dialyzer (seen in the flow direction of the used dialysis fluid) and the flow rate of the dialysis fluid, the waiting time can be zero if the dead time .DELTA.t is virtually zero, or preferably greater than / equal to the dead time .DELTA.t. If, in this case, one of the pressure threshold values PV, AV is reached during the blood flow change time t at a current blood flow, then it would then only be waited for the time tx whether there is a parameter extreme on the dialysis side. If so, the actual blood flow in question (less the current blood flow) would be determined. Otherwise, the current blood flow would be the optimal.

It should be mentioned at this point that the blood flow optimum value can also be slightly smaller than the current / actual measured blood flow for which one of the pressure threshold values PV, AV or the parameter extreme has been reached.

It should also be noted that the waiting time tx does not necessarily have to correspond to the dead time Δt. In particular, the following applies: waiting time tx greater than or equal to dead time Δt. Preferably: waiting time tx = x * Δt (with x greater than / equal to 1).

• bei dem eingestellten maximalen Blutfluss (1. Kriterium) oder
• ca. bei dem Blutfluss, in welchem der maximal zulässige arterielle Druck/venöse Druck (2. Kriterium) erreicht wird oder
• ca. bei dem Blutfluss, in welchem ein Parameterextrem (3. Kriterium) auftritt/auftrat, betrieben wird (entsprechend dem Kriterium, das zuerst erfüllt ist), auch dann, wenn sich das Parameterextrem (3. Kriterium) erst zeitlich verzögert zu den anderen Kriterien einstellt und daher ein ggf. bereits abgespeicherter (vorläufiger) Blutflussoptimalwert Qb_optimum (resultierend aus dem 1. oder 2. Kriterium) in jenen Blutflusswert reduziert wird, bei dem das (erst nachträglich) ermittelte Parameterextrem (3. Kriterium) aufgetreten ist.

The blood purification machine can either

• at the set maximum blood flow (1st criterion) or
• Approx. at the blood flow, in which the maximum permissible arterial pressure / venous pressure (2nd criterion) is reached or
• approx. at the blood flow in which a parameter extremum (3rd criterion) occurs / is operated (according to the criterion that is met first), even if the parameter extremes (3rd criterion) delayed only to the other Therefore, a possibly already stored (provisional) blood flow optimal value Qb_optimum (resulting from the 1st or 2nd criterion) is reduced to the blood flow value at which the (later) determined parameter extreme (3rd criterion) has occurred.

• Schritt d) im Verlauf der vorgegebenen Wartezeit tx (theoretisch angenommener Wert, welcher der tatsächlichen Verzögerungszeit entsprechen kann oder diese zumindest annähert) nach Schritt c) kontinuierlich oder getaktet ausgeführt wird, wenn in Schritt c) ein Schwellenwert erreicht wird;
• die Blutflussänderungsrate von einem vorgegebenen/eingebbaren Blutflussanfangswert Qb_start, dem vorgegebenen/eingebbaren Blutflusszielwert Qb_ziel, und ggf. der vorgegebenen Blutflussänderungsdauer t, abhängig eingestellt wird;
• der vorgegebene Blutflussanfangswert, Qb_start, 50ml/min und vorzugsweise der vorgegebene Blutflusszielwert Qb_ziel, max. 600ml/min beträgt;
• der Blutflusszielwert Qb_ziel, als Defaultwert in einer Steuereinrichtung abgespeichert ist, über eine Kommunikationseinrichtung eingegeben wird, von einer Patientenkarte eingelesen wird oder von einem Server übertragen wird;
• die Totzeit Δt in Abhängigkeit von der Blutflussänderungsrate, dem Blutflusszielwert Qb_ziel, einem Dialysierflüssigkeitsfluss Qd, und Parametern der extrakorporalen Blutbehandlungs-/-reinigungsmaschine, vorzugsweise Dialysemaschine (siehe vorzugsweise Parameterdefinition gemäß nachfolgender Figurenbeschreibung) vorgegeben ist;
• die Parameter der extrakorporalen Blutbehandlungsmaschine mit Hilfe der Kommunikationseinrichtung eingegeben werden, von einem Barcode eingelesen werden oder von einem Server, der Behandlungseinstellungen für Patienten enthält, geladen werden;
• die Totzeit Δt, und der Blutflusszielwert, Qb_ziel, als Wertepaare in Abhängigkeit von Parametern der extrakorporalen Blutbehandlungsmaschine in einer Wertetabelle abgespeichert sind.

The blood treatment machine can have, as a further feature or as a combination of further features, as far as this is technically possible and meaningful, that

• Step d) in the course of the predetermined waiting time tx (theoretically assumed value which may correspond to or at least approximates the actual delay time) after step c) is carried out continuously or clocked, if a threshold value is reached in step c);
• the blood flow change rate is set to be dependent on a predetermined / inputable blood flow initial value Qb_start, the predetermined / inputable blood flow target value Qb_ziel, and possibly the predetermined blood flow change duration t;
• the predetermined initial blood flow value, Qb_start, 50 ml / min, and preferably the predetermined blood flow target value Qb_ziel, max. 600ml / min;
• the blood flow target value Qb_ziel, which is stored as a default value in a control device, is input via a communication device, read in by a patient card or transmitted by a server;
• the dead time .DELTA.t is given as a function of the blood flow rate of change, the blood flow target value Qb_ziel, a dialysis fluid flow Qd, and parameters of the extracorporeal blood treatment / cleaning machine, preferably dialysis machine (see preferably parameter definition according to the following description of the figures);
• the parameters of the extracorporeal blood treatment machine are input by means of the communication device, read from a barcode or loaded by a server that contains treatment settings for patients;
• the dead time .DELTA.t, and the blood flow target value, Qb_ziel, as value pairs depending on parameters of the extracorporeal blood treatment machine are stored in a value table.

• einen Dialysator zum Blutreinigen,
• wenigstens eine Blutpumpe zum Erzeugen eines extrakorporalen Blutflusses zwischen einem Patienten und dem Dialysator,
• wenigstens eine Dialysierflüssigkeitspumpe zum Versorgen des Dialysators mit einer Dialysierflüssigkeit,
• wenigstens einen venösen Blutdruckaufnehmer stromab (unterhalb) des Dialysators,
• wenigstens einen arteriellen Blutdruckaufnehmer stromauf (oberhalb) des Dialysators,
• wenigstens einen Dialysierflüssigkeitssensor zum Erfassen wenigstens eines Dialysierflüssigkeitsparameters (z.B. UV-Absorption/-Absorbanz) unterhalb (stromab) des Dialysators in einem bestimmten Strömungsabstand zum Dialysator,
• optional wenigstens einen Blutflusssensor zum Erfassen des extrakorporalen Blutflusses falls dieser nicht mittels der Pumpe gezielt einstellbar ist,
• optional wenigstens einen Dialysierflüssigkeit-Flusssensor zum Erfassen eines Dialysierflüssigkeitsflusses falls dieser nicht mittels der Pumpe gezielt einstellbar ist.

The extracorporeal blood treatment / cleaning machine, preferably dialysis machine, preferably has the following features for carrying out the control method described above:

• a dialyzer for blood purification,
• at least one blood pump for generating extracorporeal blood flow between a patient and the dialyzer,
• at least one dialysis fluid pump for supplying the dialyzer with a dialysis fluid,
• at least one venous blood pressure transducer downstream of (below) the dialyzer,
• at least one arterial blood pressure transducer upstream (above) of the dialyzer,
• at least one dialysis fluid sensor for detecting at least one dialysis fluid parameter (eg, UV absorption / absorbance) below (downstream) the dialyzer at a specific flow distance to the dialyzer,
• Optionally at least one blood flow sensor for detecting the extracorporeal blood flow if it is not specifically adjustable by means of the pump,
• optionally at least one dialysis fluid flow sensor for detecting a dialysis fluid flow if it is not selectively adjustable by means of the pump.

• eine Kommunikationseinrichtung zum Vorgeben eines extrakorporalen Blutflusszielwertes Qb_ziel, und optional eines extrakorporalen Blutflussstartwertes Qb_start und
• eine Regel-/Steuereinrichtung zum Einstellen/Justieren eines extrakorporalen Blutflusswertes des Blutflusses (in Abhängigkeit von dem Blutflusszielwert Qb_ziel), die aufweist:
• ein Steuermittel zum Verändern (Erhöhen/ggf. Verringern) des extrakorporalen Blutflusses Qb, mit einer vorgegebenen oder ausgewählten Blutflussänderungsrate,
• einen Vergleicher zum Vergleichen eines (aktuell gemessenen) venösen Drucks PV mit einem vorgegebenen oder ausgewählten venösen Druckschwellenwert, eines (aktuell gemessenen) arteriellen Drucks PA mit einem vorgegebenen oder ausgewählten arteriellen Druckschwellenwert und des aktuellen Blutflusses Qb, mit dem Blutflusszielwert, Qb_ziel,
• eine Erfassungseinrichtung zum Erfassen wenigstens eines aktuellen Dialysierflüssigkeitsparameters/- merkmals/ - eigenschaft (Grad/Menge an in einer verbrauchten Dialysierflüssigkeit enthaltenen urämischen Toxinen z.B. über UV-Absorbtion/Absorbanz),
• eine Ermittlungseinrichtung zum Ermitteln, ob der erfasste aktuelle Dialysierflüssigkeitsparameter einen Dialysierflüssigkeit-Parameterschwellenwert annähert/erreicht hat (Ermittlung des Auftretens eines Parameterextrems), und/oder
• einen Blutflussoptimalwertspeicher zum Abspeichern jenes Blutflusses als Blutflussoptimalwert Qb_optimum, bei dem der Dialysierflüssigkeit-Parameterschwellenwert (Parameterextrem) erreicht worden ist, oder zum vorläufigen Abspeichern jenes Blutflusses als Blutflussoptimalwert Qb_optimum, bei dem der venöse Druckschwellenwert bzw. der arterielle Druckschwellenwert erreicht worden ist (und der Dialysierflüssigkeit-Parameterschwellenwert noch nicht erreicht worden ist) oder zum Abspeichern des extrakorporalen Blutflusszielwertes Qb_ziel als Blutflussoptimalwert Qb_optimum, falls weder der Parameterschwellenwert noch der venöse Druckschwellenwert bzw. der arterielle Druckschwellenwert (vorher) erreicht wurden.
• Die Regel-/Steuereinrichtung kann zudem erfindungsgemäß dazu ausgelegt sein, zumindest die Erfassungs- und Ermittlungseinrichtung auch dann noch weiter über eine Wartezeit tx zu betreiben, selbst wenn der Vergleicher das Erreichen des extrakorporalen Blutflusszielwerts Qb_ziel oder des ausgewählten venösen / arteriellen Druckschwellenwerts zu einem bestimmten Zeitpunk, in welchem die Wartezeit tx gestartet wird, erkannt hat (und damit der Anstieg des Blutflusses gestoppt wurde), um nachträglich den bereits abgespeicherten vorläufigen Blutflussoptimalwert Qb_optimum auf jenen Blutflusswert zu justieren/verändern (wieder zu reduzieren), bei dem ggf. ein Paramterextrem zeitlich um eine Verzögerungszeit/Totzeit Δt verzögert, ermittelt wird. Für das Verhältnis zwischen Wartezeit tx und Totzeit Δt gelten die vorstehenden Definitionen.

The blood treatment machine, such as a dialysis machine, may have one or more of the following features:

• a communication device for specifying an extracorporeal blood flow target value Qb_ziel, and optionally an extracorporeal blood flow start value Qb_start and
• a control / control device for setting / adjusting an extracorporeal blood flow value of the blood flow (in dependence on the blood flow target value Qb_ziel), comprising:
• a control means for changing (increasing / possibly decreasing) the extracorporeal blood flow Qb, at a predetermined or selected blood flow rate,
• a comparator for comparing a (currently measured) venous pressure PV with a predetermined or selected venous pressure threshold, a (currently measured) arterial pressure PA with a predetermined or selected arterial pressure threshold and the current blood flow Qb, with the blood flow target, Qb_ziel,
• a detection device for detecting at least one current dialysis fluid parameter / characteristic / property (degree / amount of uremic toxins contained in a used dialysis fluid, eg via UV absorption / absorbance),
• a determination device for determining whether the detected current dialysis fluid parameter has approached / reached a dialysis fluid parameter threshold (determination of the occurrence of a parameter extremum), and / or
• a blood-flow optimal value memory for storing that blood flow as blood-flow optimum value Qb_optimum at which the dialysis fluid parameter threshold (parameter extender) has been reached, or for provisionally storing that blood flow as blood-flow optimum value Qb_optimum at which the venous pressure threshold or arterial pressure threshold has been reached (and dialysis fluid Parameter threshold value has not yet been reached) or for storing the extracorporeal blood flow target value Qb_ziel as the blood flow optimal value Qb_optimum if neither the parameter threshold nor the venous pressure threshold or the arterial pressure threshold (before) has been reached.
• According to the invention, the regulating / control device can also be designed to operate at least the detection and determination device even further over a waiting time tx, even if the comparator reaches the extracorporeal blood flow target value Qb_ziel or the selected venous / arterial pressure threshold value at a specific time point , in which the waiting time tx is started, has recognized (and thus the increase in blood flow was stopped) in order to subsequently adjust / change (again reduce) the already stored provisional blood flow optimum value Qb_optimum to that blood flow value at which a paramterextrem is delayed in time by a delay time / dead time Δt. For the relationship between waiting time tx and dead time Δt the above definitions apply.

• die Steuereinrichtung eine Zeitverlängerungseinheit hat zum Verlängern des Ermittelns durch die Ermittlungseinrichtung gegenüber dem Vergleichen durch den Vergleicher um die vorgegebene oder einstellbare Wartezeit, tx, insbesondere wenn vom Vergleicher das Erreichen/Überschreiten eines Schwellenwerts erkannt wird/wurde;
• das Steuermittel vorzugsweise in Form einer Blutpumpensteuereinheit die Blutflussänderungsrate in Abhängigkeit von einem vorgegebenen Blutflussanfangswert Qb_start dem Blutflusszielwert, Qb_ziel und einer vorgegebenen Blutflussänderungsdauer t berechnet/auswählt;
• das Steuermittel, vorzugsweise die Blutpumpensteuereinheit den vorgegebenen Blutflussanfangswert Qb_start auf 50ml/min festsetzt und optional den Blutflusszielwert Qb_ziel auf > 50 bis max. 600ml/min festsetzt;
• das Steuermittel, vorzugsweise die Blutpumpensteuereinheit den Blutflusszielwert Qb_ziel als Defaultwert in einer Steuereinrichtung ausliest, von einer Kommunikationseinrichtung einliest, von einer Patientenkarte einliest oder von einem Server einliest;
• die Zeitverlängerungseinheit die Wartezeit tx in Abhängigkeit von der Totzeit Δt bestimmt, die sich aus der Blutflussänderungsrate, dem Blutflusszielwert Qb_ziel einem Dialysierflüssigkeitsfluss Qd und Parametern der Blutbehandlungsmaschine / Dialysemaschine ergibt;
• die Zeitverlängerungseinheit die Wartezeit tx aus einer Wertetabelle einliest, wobei in der Wertetabelle die Wartezeit tx oder die Totzeit Δt und der Blutflusszielwert Qb_ziel als Wertepaare in Abhängigkeit von Parametern der Blutbehandlungsmaschine / Dialysemaschine abgespeichert sind.

Preferred embodiments of the blood treatment machine according to the invention, in particular the dialysis machine, have, as a further feature or as a combination of further features, as far as this is technically possible and sensible, that

• the control device has a time extension unit for extending the determination by the determination device to the comparison by the comparator by the predetermined or adjustable waiting time, tx, in particular if the comparator detects the reaching / exceeding of a threshold value;
• the control means preferably in the form of a blood pump control unit calculates / selects the blood flow change rate as a function of a predetermined initial blood flow value Qb_start the blood flow target value, Qb_ziel and a predetermined blood flow change time t;
• the control means, preferably the blood pump control unit, sets the predetermined initial blood flow value Qb_start to 50 ml / min and optionally sets the blood flow target value Qb_ziel to> 50 to max. 600ml / min prices;
• the control means, preferably the blood pump control unit reads out the blood flow target value Qb_ziel as a default value in a control device, reads it from a communication device, reads it from a patient card or reads it from a server;
• the time-prolonging unit determines the waiting time tx in response to the dead time Δt resulting from the blood flow change rate, the blood-flow target value Qb_ziel, a dialyzing fluid flow Qd, and parameters of the blood-processing machine / dialysis machine;
• the time-prolonging unit reads in the waiting time tx from a value table, wherein in the value table the waiting time tx or the dead time Δt and the blood-flow target value Qb_ziel are stored as value pairs depending on parameters of the blood treatment machine / dialysis machine.

• Dem Arzt wird eine bessere Einschätzung des zu wählenden Blutflusses für eine Behandlung ermöglicht. Es wird ein schnelles Online-Verfahren zur Blutflussfindung ermöglicht. Das Anlegen und Regeln des Blutflusses beispielsweise bei einer Dialysebehandlung kann mit dem erfindungsgemäßen Verfahren automatisch ablaufen.
• Der Blutfluss wird zur Maximierung der dialysierflüssigkeitsseitigen Toxinmenge unmittelbar (online) angepasst. Dazu wird die dialysierflüssigkeitsseitige Toxinmenge mittels eines optischen Sensores (online) überwacht. Ebenfalls wird (online) der arterielle und venöse Druck mittels Drucksensoren an der Blutbehandlungsmaschine / Dialysemaschine überwacht, um die Sicherheit zu gewährleisten.

The invention has the following advantages, among others:

• The doctor is given a better assessment of the blood flow to be selected for treatment. It provides a fast online blood flow finding process. The creation and regulation of the blood flow, for example during a dialysis treatment, can take place automatically with the method according to the invention.
• Blood flow is adjusted to maximize dialysis fluid side toxin level immediately (online). For this purpose, the dialyzing liquid-side toxin amount is monitored by means of an optical sensor (online). Also, the arterial and venous pressure is monitored (online) by means of pressure sensors on the blood treatment machine / dialysis machine to ensure safety.

Further features and advantages of the invention will become apparent from the following description of preferred embodiments, wherein reference is made to the accompanying drawings.

figure description

• Fig. 1 shows schematically an embodiment of the blood treatment machine / dialysis machine according to the invention.
• Fig. 2 To illustrate, the course of clearance to the blood flow with and without disturbing effect.
• Fig. 3 To illustrate, the course of the extinction in the dialysis fluid compared to the blood flow with and without disturbing effect.
• Fig. 4 shows an embodiment of a (machine control) method for adjusting the current blood flow in a dialysis.
• Figs. 5A and 5B each illustrate schematically the path of a possible disturbance in a dialysis system.
• FIGS. 6A and 6B in each case schematically illustrate the determination of an extreme value in the intensity signal of a dialysis fluid sensor in a dialysis system.
• Fig. 1 13 shows the schematic flow plan of an extracorporeal blood treatment / cleaning machine / dialysis machine with a control device 15 in conjunction with a communication device 16. A blood pump 7 takes blood from a patient's body via a patient access (shunt puncture site) which is located in Fig. 1 is schematically indicated on the right as patient forearm. The current blood pump rate can optionally be additionally determined with a flow sensor 13 on the extracorporeal blood side. An arterial pressure transducer 6 monitors the current negative pressure on the suction side of the blood pump 7.

The blood pump 7 conveys the patient's blood through a dialyzer 4, whereby uremic toxins can pass from a blood side 10 to a dialysis fluid side 11 of the dialyzer 4 through a semipermeable membrane (not shown). The blood thus purified is then returned to the patient. A venous pressure transducer 5 monitors the venous pressure within the extracorporeal blood circuit downstream of the dialyzer 4.

Dialysis fluid pumps 2 and 9 generate the dialysis fluid flow through the dialyzer 4 on its dialysis fluid side 11. As a result, in the dialyzer 4 on the Dialysierflüssigkeitsseite 11 passed uremic toxins past an optical sensor 8, which is the dialyzer 4 dialysis fluid side preferably immediately downstream. The amount of uremic toxins which have passed over the dialysis fluid side 11 can be measured by means of the optical sensor (UV sensor) 8. The intensity I or absorbance A in the used dialysis fluid is a measure of the current cleaning performance of the blood treatment machine / dialysis machine.

The used dialysis fluid flows through the optical sensor 8 with a defined dialysis fluid flow Qd, which is measured with a flow sensor 12 on the dialysis fluid side and which in the present case is preferably immediately upstream of the dialyzer 4.

The hydraulic / fluidic structure of the above-described blood treatment machine / dialysis machine largely corresponds to the prior art and is therefore basically known. The operation of the blood treatment machine / dialysis machine is also known per se from the prior art, so that the detailed description of the individual processes occurring at the dialyzer 4 can be omitted here.

The cleaning performance of the dialyzer 4 should be as high as possible in the rule. Since the extracorporeal blood flow, in addition to the dialysis fluid flow and the quality of the dialyzer 4 represents one of the manipulated variables for maximizing the cleaning performance of the blood treatment machine / dialysis machine, the present invention is described Apparatus and method according to the invention for maximizing cleaning performance by adjusting extracorporeal blood flow.

For this purpose, by means of the optical sensor 8, the dialysis fluid-side equalization process is analyzed during and after completion of a defined blood flow change with the aid of the optical sensor 8. In principle, it is therefore a transient measurement that is suitable for hemodialysis (HD), hemodiafiltration (HDF), hemofiltration (HF) as well as single needle crossover (SNCO) for the optimization of blood flow.

Fig. 1 shows which units of the machine are necessary for the implementation of the blood flow control according to the invention and in what way they communicate. An electronic communication device 16 serves the user on the one hand to display and on the other hand to enter treatment parameters (corresponding to the parameters of the blood treatment machine), such as blood flow (start and / or target blood flow), dialysis fluid flow and / or pressure limits in the area of blood output and blood input and in the patient. This happens, for example, via a graphic user interface of the machine, by means of a patient card or via data transmission of the patient-specific treatment settings from an external patient data server.

These inputs are used by the controller 15 to control and / or regulate the pumps 2, 9, 7 and / or valves not shown further. For z. T. resorted to information provided by the (blood) pressure sensors 5, 6, the flow sensor 12 on the dialysis fluid side, the flow sensor 13 on the blood side and the optical sensor 8 are available. The controller 15 also serves to pre-process the data provided by the sensors. The preprocessing includes z. B. filtering and smoothing the data (signals) or the extraction of parameters. In addition, the control device 15 serves to store all treatment parameters (machine parameters), but also to store all the information necessary to be able to use the method for optimized blood flow adjustment. An example of this is dialyzer-specific data, such as the blood-side volume (Vb) and the volume to be dialysed (Vd) of the dialyzer 4, but also all other characteristics and maps (eg., Dialysatorclearance, etc.) are included.

The dialyzer 4 and the extracorporeal tubing / blood line system must be properly identified for the application. This can be done for example by means of the communication device 16, z. B. by entering the. Dialysatormodels by the user or reading a barcode attached to the dialyzer 4. Alternatively, it would still be possible to generate a defined volume by automatic level setting in the dialyzer chambers.

The communication between all modules such as control device 15, communication device 16, the individual actuators / pumps 2, 9, 7, etc. can be unidirectional or bidirectional.

mit Ce als der effektiven Clearance "aus Patientensicht" (entspricht nicht notwendiger weise der Dialysator-Clearance), R als Rezirkulation und Cd als Clearance des Dialysators. Das bedeutet, dass die effektive Clearance beim Auftreten von Rezirkulation / Shunt-Rezirkulation deutlich hinter der reinen Dialysator-Clearance zurückbleibt, die für R = 0 gleich der effektiven Clearance wäre.The intensity or absorbance of the used dialysis fluid is a direct measure of the amount of uremic toxins that pass from blood to the dialysis fluid side. Often, it is assumed that an increase in extracorporeal blood flow (Qb) is always accompanied by an increase in effective clearance (Ce). An increase in clearance would therefore result in a greater amount of uremic toxins on dialysis fluid side and could be detected by a higher absorbance of the used dialysis fluid. However, this assumption is only valid if no complications occur that reduce the amount of uremic toxins already at the vascular access of the patient. Such a complication, such as a local recirculation or shunt recirculation, has the consequence that the amount of uremic toxins that find their way to the dialysis fluid side, despite increasing blood flow does not increase or not to the same extent, but remains the same, for example less strongly increases or even sinks. The relationship between clearance Ce and recirculation can be described as follows: $$\mathrm{Ce}=\left(\mathrm{1}-\mathrm{R}\right)\mathrm{CD}/\left(\mathrm{1}-\mathrm{R}\left(\mathrm{1}-\mathrm{CD}/\mathrm{Qb}\right)\right)$$

with Ce as the "patient-view" effective clearance (not necessarily the dialyzer clearance), R as recirculation and Cd as clearance of the dialyzer. This means that the effective clearance when recirculation occurs / Shunt recirculation remains well behind pure dialyzer clearance, which would be equal to effective clearance for R = 0.

Fig. 2 Figure 4 shows an example of the reduction of the effective clearance Ce of a dialyzer assuming that a recirculation of 20% occurs at a blood flow of 300 ml / min.

In Fig. 2 the clearance is shown as a function of blood flow Qb according to equation (1). As blood flow Qb increases, the effective clearance also increases. The clearance has a non-linear and for the recirculation-free case a monotonously increasing course. However, if there is a recirculation at the patient access, then the recirculation effects reduce the effective clearance Ce, which in Fig. 2 as the line branching off / deviating downwards from the theoretical / ideal effective clearance at high Qb values.

Fig. 3 shows by way of example an example of a so-called. Steady-state absorbance, measured at about 285nm behind the dialyzer 4. Shown is the dialysis fluid absorbance on the blood flow. At high Qb values, the decrease in absorbance due to recirculation effects is plotted as the falling line.

Absorbance is equivalent to the amount of uremic toxins removed from the blood. The purification performance is therefore maximal when the amount of toxins on the dialysis fluid side for defined Qb, Qd is maximum. Thus, the cleaning line is also maximum when the absorbance is maximum or the intensity at the measuring channel of the sensor is minimal.

Fig. 4 shows an embodiment of a method. In the method, the combination of a, preferably linear, blood flow change, the analysis of the pressure signals and the optical measurement of the most advantageous for the treatment blood flow is found.

• 17 Vorgeben eines Blutflusszielwerts Qb_ziel,
• 18 Verändern des Blutflusses Qb mit einer vorgegebenen, ggf. linearen Blutflussänderungsrate vorzugsweise durch eine Blutpumpensteuereinheit oder ein Stromregelventil, oder dergleichen,
• 19 Vergleichen eines (blutseitigen) venösen Drucks PV mit einem ausgewählten oder vorgegebenen venösen Druckschwellenwert und eines (blutseitigen) arteriellen Drucks PA mit einem ausgewählten oder vorgegebenen arteriellen Druckschwellenwert,
• 20 Vergleichen des aktuellen Blutflusses Qb mit dem Blutflusszielwert Qb_ziel, vorzugsweise durch eine Vergleichereinheit,
• 21 Erfassen wenigstens eines Dialysierflüssigkeitsparameters (z.B. Absorbanz) sowie vorzugsweise Nachverfolgen des Parameterverlaufs durch eine Erfassungseinrichtung und Ermitteln eines möglichen Auftretens eines Parameterextrems durch eine Ermittlungseinrichtung,
• 22 Abspeichern eines Blutflussoptimalwertes Qb_optimum basierend auf den Ergebnissen in den Schritten 19 bis 21,
• 23 Betreiben der Maschine mit dem Blutflussoptimalwertes Qb_optimum bis auf weiteres,
• 24 Betreiben der Maschine mit dem Blutflusswert Qb_P_grenz - x% während einer vorgegebenen Wartezeit tx,
• 25 Nachträgliches/fortlaufendes Ermitteln eines möglichen Auftretens eines Parameterextrems durch die Ermittlungseinrichtung zumindest in der Wartezeit tx oder darüber hinaus,
• 26 Neuberechnen/Nachjustieren des Blutflusswertes Q_b (im Fall des nachträglich ermittelten Auftretens eines Parameterextrems)
• 27 Betreiben der Maschine mit dem Blutflusszielwert Qb_ziel während einer vorgegebenen Wartezeit tx,
• 28 Nachträgliches/fortlaufendes Ermitteln eines möglichen Auftretens eines Parameterextrems durch die Ermittlungseinrichtung zumindest in der Wartezeit tx oder darüber hinaus,
• 29 Neuberechnen/Nachjustieren des Blutflusswertes Q_b (im Fall des nachträglich ermittelten Auftretens eines Parameterextrems) und
• 30 Neuberechnen/Nachjustieren des Blutflusswertes Q_b (im Fall des ermittelten Auftretens eines Parameterextrems).

The embodiment of the (machine control) method according to Fig. 4 indicates the steps starting from a selected or preset blood flow start value Qb_start

• 17 prescribing a blood flow target value Qb_ziel,
• 18 changing the blood flow Qb at a predetermined, possibly linear blood flow rate, preferably by a blood pump control unit or a flow control valve, or the like,
• 19 comparing a (blood-side) venous pressure PV with a selected or predetermined venous pressure threshold and a (blood-side) arterial pressure PA with a selected or predetermined arterial pressure threshold,
• 20 comparing the current blood flow Qb with the blood flow target value Qb_ziel, preferably by a comparator unit,
• 21 detecting at least one dialysis fluid parameter (eg absorbance) and preferably tracking the parameter course by a detection device and determining a possible occurrence of a parameter extremum by a detection device,
• 22 storing a blood flow optimum value Qb_optimum based on the results in steps 19 to 21,
• 23 operating the machine with the blood flow optimal value Qb_optimum until further notice,
• 24 operating the machine with the blood flow value Qb_P_grenz - x% during a predetermined waiting time tx,
• 25 Subsequent / continuous determination of a possible occurrence of a parameter extremum by the determination device at least in the waiting time tx or beyond,
• 26 Recalculating / readjusting the blood flow value Q_b (in the case of the subsequently determined occurrence of a parameter extreme)
• 27 operating the machine with the blood flow target value Qb_ziel during a predetermined waiting time tx,
• 28 Subsequent / continuous determination of a possible occurrence of a parameter extremum by the determination device at least in the waiting time tx or beyond,
• 29 Recalculating / readjusting the blood flow value Q_b (in the case of the subsequently determined occurrence of a parameter extreme) and
• 30 Recalculating / readjusting the blood flow value Q_b (in the case of the determined occurrence of a parameter extreme).

These steps are explained below.

In step 17, a blood flow target, Qb_ziel, is entered (e.g.,> 50-600 ml / min). The blood flow target value, Qb_ziel, may be stored as a default value in the control device 15, entered via the communication device 16, read in by a patient card (not shown), or transmitted by a server (not shown).

In step 18, within a predetermined time t, the current blood flow Qb is raised from a predetermined value Qb_start (e.g., 50 ml / min) to the value Qb_ziel (continuously or incrementally at a certain rate of increase). The predetermined value Qb_start is e.g. 50ml / min and is fixed while the value Qb_ziel (e.g., 300ml / min) may be predetermined by the user via the communication device 16 as described above or transmitted from a patient card or a server.

1. i. Erreichen/Überschreiten eines der Druckwertgrenzen (oberer Grenzwert venöser Druck PV und/oder unterer Grenzwert arterieller Druck PA im extrakorporalen Blutkreis),
2. ii. Auftreten eines Intensitätsminimums bzw. Absorbanzmaximums im Signal des optischen Sensors,
3. iii. Erreichen/Überschreiten des angeforderten hohen Blutflussniveaus Qb_ziel.

The control device 15 continuously or clocked parameters are queried, which serve as Abbruch- or control criteria for blood flow increase. These criteria are:

1. i. Reaching / exceeding one of the pressure value limits (upper limit venous pressure PV and / or lower limit value of arterial pressure PA in the extracorporeal blood circuit),
2. ii. Occurrence of an intensity minimum or absorbance maximum in the signal of the optical sensor,
3. iii. Reaching / exceeding the requested high blood flow level Qb_ziel.

In step 19, a query is therefore made as to whether an upper limit value for the venous pressure, PV, or a lower limit value for the arterial pressure, PA, has been reached / exceeded.

In step 20, it is also queried whether the target value of the blood flow, Qb_ziel, has been reached. The target value of the blood flow, Qb_ziel, can, as mentioned above, be set manually by the user via the communication device 16 or be predetermined as a default value, the default value being loaded from the control device 15.

Similarly, in step 21 it is queried whether an intensity minimum I_min or absorbance maximum A_max in the signal of the optical sensor 8 for the concentration of uremic toxins in the dialysis fluid below the dialyzer 4 has been identified.

Fig. 4 shows the further steps of the method in dependence on which of the queries 19 to 21 a branch of the process is reached first.

If the query in step 19 is yes, i. the achievement of one of the two limiting pressures PV and PA is detected, a blood flow is set (initially temporary), in which the pressure remains within the pressure limits. This blood flow is then kept constant for a waiting time tx. This waiting time tx corresponds approximately to an expected delay or dead time, which elapses until a parameter extrema adjusting on the dialyzer 4 via the dialysis discharge line from the dialyzer 4 to the (absorption) sensor 8 is needed. Independently of this, the signal of the optical sensor 8 is optionally further evaluated permanently until the balancing process on the dialysis fluid side has been completed completely, i. until a stable end level has set and the signal at the optical sensor 8 no longer changes.

If no extreme value in the form of an intensity minimum or absorbency maximum is identified by the control device 15, then the (initially preliminary) constant adjusted blood flow is also the optimal blood flow for the treatment. This is queried in step 25, after which the process proceeds directly to step 22 if the result is negative. In step 22, the optimal blood flow is stored as a blood flow optimal value Qb_optimum in a blood flow optimum value memory, and the machine is finally set to this value in step 23. The procedure is now complete and will be terminated.

If, in contrast, an extreme value in the form of an intensity minimum or absorbance maximum in the signal of the optical sensor is detected by the control device 15 in step 25, the optimal blood flow is calculated on this basis. In this case, the blood flow is calculated (reconstructed) by the control device 15 with the aid of the time at which the extremum occurs or has occurred (occurrence time). This takes place in step 26, in which the blood flow is then present as a new blood flow value Q_b.

If it is determined in step 21 that an intensity maximum I_min or an absorbance minimum A_max has been reached, the controller 15 detects, for example during the evaluation of the transient signal from the optical sensor 8, the occurrence of an extreme value (delayed). On this basis, the control device 15 in step 30 and the steps 22 and 23 then calculate the new blood flow value Q_b and therefrom the optimal blood flow blood flow optimum value Qb_optimum.

If it is determined in step 20 that the blood flow target value Qb_ziel for the blood flow has been reached (initially without an extreme value has been determined), the blood flow is kept constant in step 27 for a waiting time tx (provisionally). The signal of the optical sensor 8 is still evaluated by the control device 15.

Should be subsequently, i. After the preliminary setting of the blood flow to the blood flow target value Qb_ziel (delayed), preferably within the waiting time tx, a parameter extremum is still to be determined, in this case a new blood flow value Q_b is calculated in step 29 (corresponds approximately to that blood flow which actually occurs in the extreme and, in turn, the blood flow optimum value Qb-optimum is determined in step 22, and in step 23 the machine is operated until further notice with this value, so that the method ends therewith. If no extreme value could be found / determined in the form of an intensity minimum or absorbency maximum by the control device 15 preferably within the waiting time tx or beyond, a return to step 18 follows in step 28 and the blood flow is further increased until either step 19 the venous threshold value PV or the arterial threshold value PA is reached or in step 21 the dialysis fluid threshold value I_min or A_max is reached. Alternatively, however, the attending physician or the supervising bediner person could also be requested to specify the blood flow target value Qb_ziel.

The monitoring of the pressure values PV, PA serves the purpose of not exceeding the permissible lower arterial or upper venous pressure, and thus patient safety. Both pressures are determined by the interaction of needles, Puncture situation and vessel status of the patient influenced. The monitoring of the pressure values is carried out by the control device 15.

The optical sensor 8 on dialysis fluid side measures the intensity or the absorbance of the used dialysis fluid, depending on the flushed uremic toxins dissolved therein. The control device 15 searches for an extreme point in the sensor signal, which only occurs when complications occur, e.g. local recirculation, such as shunt recirculation,

• Die Werte zur Beurteilung der Abfrage 20 "Qb_ziel erreicht?" und der Abfrage 19 "PV oder PA erreicht?" sind sofort verfügbar. Dies gilt jedoch nicht in gleichem Maße für die Daten des optischen Sensors 8.

The signals of the pressure sensors 5, 6 and the optical sensor 8 are the basis for the actions which are triggered by the control device 15. All sensor data can be edited by the control device 15, for example, be smoothed or filtered by a low-pass filter. Fig. 4 shows specifically for the query 20 "Qb_ziel reached?" and query 19 "PV or PA reached?" that subsequently can not be concluded immediately on the optimal blood flow. The cause of this is the following:

• The values to judge the query 20 "Qb_ziel reached?" and query 19 "PV or PA reached?" are available immediately. However, this does not apply to the same extent to the data of the optical sensor 8.

The time sequence of a pressure change and the reaction at the optical sensor 8 will be described below with reference to FIG Figs. 5A and 5B explained. In Fig. 5A the direction is schematically indicated, in which the processes are explained below. The patient is at the entrance of the system. It is connected to the dialyzer 4 via a blood-side tube system. The dialyzer 4 is in turn connected via a further dialysis-side tube system with the optical sensor 8, which monitors predetermined parameters (absorbance, absorption, etc.) of the output side, used dialysis fluid. In the case of a change in the patient, eg a local recirculation, such as shunt recirculation with reduction of the effective clearance, this change does not have to be noticeable until the distance to the optical sensor. This means that the transport must take place through the arterial tube section, the dialyzer and the dialysis fluid-side tubing, before the effect of this change on the system input (patient access) can be detected by the optical sensor 8. This time delay is in Fig. 5B played.

In Fig. 5B the waveform is plotted over time. Out Fig. 5B shows that the effect of local recirculation on the patient access, such as shunt recirculation for the optical sensor 8, can only be measured with considerable time delay. Therefore, a wait time after query 20 "Qb_ziel reached?" or query 19 "PV or PA reached?" provided before the query 27 or 28 "I_min or A_max reached?", To avoid that the wrong blood flow is set.

That means that like out Figs. 5A and 5B seen systemic change that occurs at the patient access / shunt of the patient, only then can be detected by the optical sensor 8, when they have passed through the Schlausystem blood side, the dialyzer 4 and the dialysis fluid side distance to the sensor 8. Therefore, an event that occurs at time t is detected only with delay (dead time) at time t + Δt.

In FIGS. 6A and 6B the determination of blood flow is explained as an example. In both Figures 6A and 6B is both the increase in blood flow (rising line in FIGS. 6A and 6B ) as well as the intensity signal of the optical sensor 8 (evanescent curve in FIG FIGS. 6A and 6B ) over time. In Fig. 6A the blood flow is increased from time t1. The time t2 indicates the end of the blood flow increase, while at t3 the end of the intensity change is reached at the optical sensor 8. Since the optical sensor 8 is mounted on dialysis fluid side, there is always a time delay. Blood-side system changes that have an effect on the amount of toxin in the dialysis fluid are not immediately measurable when they appear on the optical sensor 8. Here, in addition, the transport through the blood-side tube system and the dialyzer 4 etc. must be taken into account. In addition, compensation processes occur, which are due to the volumes (blood side, dialysis fluid side) in the dialyzer 4.

In Fig. 6B the delay time is plotted in the signal. As a result of the blood flow increase, a change in concentration was induced here at the time of admission to the patient. The cause of this change in concentration may be, for example, a local recirculation / shunt recirculation. As a result, fewer substances can find their way to the dialysis fluid side. If this occurs at the time ts during the blood flow increase, initially the detected intensity begins to fall and then to increase again some time, although the blood flow is further increased (it should be noted that the intensity in principle should always decrease as a result of the blood flow increase, only the subsequent increase would mean the induction of a recirculation). In Fig. 6B shows this change in concentration by the expression of an extreme point (at time tm) in the sensor signal of the optical sensor 8. The already described delay time between the input side occurrence and the output side measurement of the effect is in Fig. 6B as Δt (and possibly corresponds to the waiting time tx, where ideally applies: .DELTA.t less than / equal to tx).

$$\mathrm{ts}=\mathrm{tm}-\mathrm{\Delta t}\mathrm{.}$$

The occurrence time tm of this extreme point is related to the time ts at which the complication occurs at the entrance. If there is a change at the entrance, the following applies: $$\mathrm{tm}>\mathrm{ts}$$

$$\mathrm{ts}=\mathrm{tm}-\mathrm{.delta.t}\mathrm{,}$$

If Δt is known, the knowledge of tm can be used to determine the optimal treatment blood flow, since this is the blood flow Qb (tm-Δt).

This dead time Δt is dependent on the selected blood flow change Qb (t) or Qb_ziel, the dialysis fluid flow Qd and the volumes involved, e.g. in the dialyzer 4 (Vbeff effective blood side volume, Vdeff effective dialysierflüssigkeitsseitiges volume) and in the tube system.

This results in: $$\mathrm{.delta.t}=\mathrm{f}\left(\mathrm{Qb}\left(\mathrm{t}\right).\mathrm{qd}.\mathrm{Vbeff}.\mathrm{Vdeff}.\mathrm{VSchlauch\_arteriell}\right)\mathrm{,}$$

Both Qb (t), Qd, Vbeff, Vdeff and VSchlauch_arteriell are known quantities, for example, taken from laboratory measurements or data sheets. For this purpose, the dialyzer 4 and the blood-side tube system is identified prior to treatment in order to access the relevant tables. The identification of the dialyzer 4 or the hose system takes place via the communication device 16 by the user, reading a barcode or loading the data from a server, etc.

If Δt is not calculated from the variables Qb, Qd, VSchlauch_arteriell, Vbeff and Vdeff, Δt is stored directly in a table, since the dependence of Δt and Qb_ziel is known from laboratory measurements, if at the same time the dialyzer 4 and the tube system (eg by user input ) have been identified. Qd must also be known. The dialysis fluid flow Qd is detected at any time by measurement. Table 1 shows an example of the assignment of the values of Δt to different Qb_ziel at a dialysis fluid flow of 500 ml / min. In this example, the dialyzer 4 and the tube system as well as the dialysis fluid flow Qd are already known. Therefore, a look-up table is used which contains the values of Δt for the respective configuration of dialyzer 4 and tubing system as well as Qd. Table 1 Qb_ziel [ml / min] Δt [s] 300 20 400 25

With the invention, a device is created for the first time, which makes an adjustment of the blood flow automatically based on the effective clearance and additionally ensures by the pressure monitoring that the patient is not endangered. Specifically, this means that the situation at the patient access, for example when creating and adjusting the blood flow can be monitored directly (online). This means that each blood-flow-induced reduction in the effective clearance can be detected (quasi) instantaneously and thus the blood flow can be adjusted to the maximum therapeutic effect. In other words, an optimization of the therapy to the maximum clearance can be achieved with the method according to the invention. Further, by analyzing the equalization process (transient measurement) on the dialysis fluid side measured by an optical sensor, control of the optimal blood flow is performed. Even with complications at the entrance the optimal dialysis treatment of every patient can be ensured. By regulating / controlling the blood flow to the maximum cleaning power and thus the Possibility to reduce the dialysis fluid flow until the desired Kt / V is achieved (indicated by Kt / V prediction), dialysis fluid can be saved. This is especially true if Kt / V is above the desired quality level. Furthermore, the process described above can be re-triggered at any time within the treatment, if desired by the treating staff (the blood flow change can be done in this direction in both directions, namely increase / decrease). By storing the blood flows found and the trend evaluation, the shunt situation can be monitored. Recirculation is automatically detected by detecting the extreme point. The measuring times can be kept short, so that the measuring time is less than four minutes. Due to the existing sensors, the expected costs can be kept low. By measuring on the dialysis fluid side nurses have no additional effort in the preparation of dialysis and inserting the blood hose system in the sensors and is also relieved by an automatic application procedure.

In a preferred embodiment (not shown), a red detector is used to detect blood during patient application. There is a blood pump rate of 50ml / min until patient access is available. A blood flow increase to a prescribed blood flow value can be initiated automatically or manually by the operator personnel (in FIGS. 6A and 6B on Qb_ziel less than or equal to 600ml / min). The optical sensor monitors the intensity in the drain, and the controller 15 continuously evaluates the signal and determines z. B. the slope. Pressure sensors monitor the permissible pressure limits. The control device 15 evaluates the data and determines the occurrence time of an extremum or determines the occurrence of another termination criterion (eg PV or PA achieved). With the aid of a look-up table such as Table 1, the value of ts is determined from tm-Δt. Choosing the right lookup table requires knowledge of dialyzer and tubing configuration as well as Qd.

The invention consists of a device and the pending method for determining the optimal blood flow, preferably at the start of therapy. This measurement can be done without additional equipment, since the dialysis machine already has all the necessary actuators and sensors. The blood flow, where a maximum of uremic substances find their way from the blood to the dialysis fluid side, is determined by achieving one of three criteria as described above when the blood flow is changed. One criterion is to reach the pressure limits PV or PA, the other criterion is to find the extreme values I_min or A_max and the last criterion is finally the achievement of the preset maximum blood flow (target blood flow). Since the blood flow can be maintained substantially at its maximum value with the method according to the invention, the dialysis fluid flow can be reduced for the same cleaning performance, so that, if necessary, a potential for savings (usually when the treatment shows that the required dialysis dose is exceeded).

The blood treatment machine / dialysis machine according to the invention consequently comprises a dialyzer 4 for blood purification. To maintain an external blood circulation, at least one blood pump 7 is provided, which generates a blood flow between a patient and the dialyzer 4. On the other side of the dialyzer 4, at least one dialysis fluid pump 2, 9 is provided, with which the dialyzer 4 is supplied with a dialysis fluid. To monitor the dialysis process, preferably at least one venous blood pressure sensor 5 is provided below (downstream) the dialyzer 4. Similarly, the blood treatment machine / dialysis machine preferably comprises at least one arterial blood pressure transducer 6 above (upstream) the dialyzer 4, and preferably at least one dialysis fluid sensor (optical sensor) 8 for detecting at least one dialysate parameter below (downstream) the dialyzer 4. On the blood side of the dialyzer 4 is preferably at least a blood flow sensor 13 is used to detect blood flow. Furthermore, the blood treatment machine / dialysis machine preferably comprises at least one dialysis fluid flow sensor 12 for detecting a dialysis fluid flow.

Via a communication device 16, a blood flow target value, Qb_ziel, is specified. A control device 15 is used to set an optimal blood flow value as a function of the preset blood flow target value, Qb_ziel, the detected upper and lower blood pressures PA, PV and the possible determination of a parameter extremes. According to the invention, the control device 15 has a blood pump control unit (not shown) for changing the blood flow, Qb, at a predetermined blood flow rate or a flow control valve. This rate is in particular (Qb_ziel - Qb_start) / t. A comparator unit (not shown) (within the controller 15) serves to compare a venous pressure PV with a venous pressure threshold, an arterial pressure PA with an arterial pressure threshold, and the current blood flow Qb with the blood flow target Qb_ziel. A determination device (not shown) (component of the control device 15) is provided for determining a parameter extremum in the used dialysis fluid from the detected parameter values from the sensor 8. A blood-flow optimum value memory (likewise not part of the control device 15) (not shown) is used to store a blood-flow optimum value Qb_optimum, for example in dependence on that blood flow which actually prevailed at the time of occurrence of the parameter extreme, and preferably on Qb_ziel and .DELTA.t (actual delay time) as a function of the look-up table, if the determination of the parameter extremity (dialysis fluid parameter threshold value) is within the waiting / extension time tx has been recognized or when the comparator unit has detected the reaching of the venous pressure threshold or the arterial pressure threshold, and v If necessary, the failure of the parameter extremum (dialysis fluid parameter threshold value) has also been detected on the determination device within the waiting / extension time tx. If none of the above conditions is met, the blood flow Qb is further changed (increased) at the predetermined blood flow rate by a return device (not shown) until the set blood flow Qb_ziel is reached.

Preferably, a delay / extension unit (part of the controller 15) (not shown) between the comparator unit and the detecting means / unit is provided for delaying / extending the detecting operation by the detecting means by the (predetermined) waiting / extension time tx, when from the Comparing unit, the reaching of a pressure threshold has been detected for the time being, as has already been described above.

In other words, after reaching a pressure threshold value, the determination unit continues the determination process by the extension time tx in order to make a decision on the existence of a parameter extremum at the end of the Extension time tx to delay. If it should then be established that no parameter excess was present in the used dialysis fluid, it remains at the initially stored blood flow at which the pressure threshold value was reached. However, if the occurrence of a parameter extreme is subsequently detected with a delay, the blood flow at the real time of the parameter extremum can be determined on the basis of the previously stored lookup table, according to which the blood flow optimum value is then defined.

Preferably, the blood pump control unit calculates the blood flow change rate as a function of a predetermined initial blood flow value Qb_start the blood flow target value Qb_ziel and a predetermined blood flow change duration, t. The blood flow target value Qb_ziel can be read out as a default value, read in by a communication device, read in by a patient card or read in by a server.

The delay / extension unit preferably determines the waiting / extension time tx as a function of the blood flow change rate, the blood flow target value Qb_ziel, a dialysis fluid flow Qd and parameters of the blood treatment machine / dialysis machine. In particular, the delay unit can read the waiting / extension time tx from the data / value table (lookup table), wherein in the data / value table the delay time .DELTA.t and the blood flow target value Qb_ziel are stored as value pairs depending on parameters of the blood treatment machine / dialysis machine, thus the condition tx ≥ Δt remains satisfied.

LIST OF REFERENCE NUMBERS

1

Dialysierflüssigkeitszulauf

2

Dialysis fluid pump at the dialysis fluid inlet

3

substitution pump

4

dialyzer

5

Pressure transducer venous

6

Pressure transducer arterial

7

blood pump

8th

Sensor, e.g. optical sensor

9

Dialysis fluid pump Dialysis fluid outlet

10

Blood side of the dialyzer

11

Dialysis fluid side of the dialyzer

12

Flow sensor dialysis fluid side

13

Flow sensor blood side

14

outflow

15

control device

16

communicator

17

Predetermining a blood flow target value, Qb_ziel, via a communication device (16),

18

Changing the blood flow, Qb, at a predetermined blood flow rate by a blood pump control unit,

19

Comparing a venous pressure, PV, with a venous pressure threshold, an arterial pressure, PA, with an arterial pressure threshold

20

Comparing the blood flow, Qb, with the blood flow target, Qb_ziel, preferably by a comparator unit,

21

Determining a dialysis fluid parameter threshold (parameter extremes), ie checking for global extreme value, which corresponds to the criterion "I _min / Abs _max ", by a determination device / determination unit,

22

Storing a blood flow optimum value, Qb_optimum,

23

Operate the machine with the blood flow optimal value, Qb_optimum, until further notice and finish the procedure

24

Operating the machine with the blood flow value Qb_P_limit - x% during a predetermined waiting time tx,

25

Determining a dialysis fluid parameter threshold (parameter extremes), ie checking for global extreme value, which corresponds to the criterion "I _min / Abs _max ", by a determination device / determination unit,

26

Calculate the new blood flow value Q_b

27

Operating the machine with the blood flow value Qb_ziel during a predetermined waiting time tx,

28

Determining a dialysis fluid parameter threshold (parameter extremes), ie checking for global extreme value, which corresponds to the criterion "I _min / Abs _max ", by a determination device / determination unit,

29

Calculate the new blood flow value Q_b

30

Calculate the new blood flow value Q_b

Claims (10)

1. An extracorporeal blood treatment machine which comprises:

   a dialyzer (4),

   at least one blood pump (7) for creating an extracorporeal blood flow between a patient and the dialyzer (4),

   at least one dialysis fluid pump (2, 9) for supplying the dialyzer (4) with a dialysis fluid,

   at least one venous blood pressure sensor (5) downstream of the dialyzer (4),

   at least one arterial blood pressure sensor (6) upstream of the dialyzer (4),

   at least one dialysis fluid sensor (8) for detecting at least one dialysis fluid parameter downstream of the dialyzer (4), and

   a control device (15) for adjusting a blood flow value of the blood flow in dependence on the blood flow target value (Qb_target), wherein

   the control device (15) comprises:

   a control/regulating unit for altering the current blood flow (Qb) at a predetermined or selected blood flow alteration rate,

   a comparator unit for comparing a venous pressure (PV) with a venous pressure threshold, an arterial pressure (PA) with an arterial pressure threshold, and the current blood flow (Qb) with the blood flow target value (Qb_target),

   a determination unit for determining a dialysis fluid parameter extreme from a number of measurement values through the dialysis fluid sensor (8),

   an optimum blood flow value memory for storing an optimum blood flow value (Qb_optimum), if a dialysis fluid parameter extreme has been determined by the determination unit, or if the comparator unit recognized that the venous pressure threshold, the arterial pressure threshold or the blood flow target value has been reached and the determination unit has not, or not yet determined a dialysis fluid parameter extreme, wherein the blood treatment machine is adapted to execute the following steps:

   a) predetermining (17) the blood flow target value (Qb_target),

   b) altering (18) the blood flow (Qb) at a predetermined or selected blood flow alteration rate,

   c) comparing (19, 20) the venous pressure (PV) with the venous pressure threshold, the arterial pressure (PA) with the arterial pressure threshold, and the current blood flow (Qb) with the blood flow target value (Qb_target) by means of the comparator unit,

   d) determining the dialysis fluid parameter extreme through the determination unit,

   wherein, after a predetermined waiting time (tx) (24, 27), step d) (21) is executed after step c) (19, 20), if a threshold is reached in step c) (19, 20), or wherein step d) (21) is executed, in a clocked mode or continuously, over a predetermined extension time (tx) (24, 27) after step c) (19, 20), if a threshold or the blood flow target value (Qb_target) is reached in step c) (19, 20).
2. Blood treatment machine according to claim 1, wherein it is configured as a dialysis machine.
3. The blood treatment machine according to claim 1 or 2, wherein a waiting/extension period (tx) is predetermined or adjustable in dependence on a delay time (Δt) between the actual occurrence of the dialysis fluid parameter extreme and its detection at a detection site, in particular in dependence on the blood flow alteration rate, the blood flow target value (Qb_target), a dialysis fluid flow (Qd) and parameters of the blood treatment machine, and the delay time (Δt) and the blood flow target value (Qb_target) are stored as pairs of values in a lookup table.
4. The blood treatment machine according to one of the preceding claims, wherein the control device (15) additionally comprises:

   a delay/extension unit for delaying/extending the determination process of the determination unit by at least a predetermined waiting/extension time (tx), if the comparator unit recognized that a threshold has been reached and if an associated blood flow has been temporarily stored as an optimum blood flow value (Qb_optimum) by the optimum blood flow value memory.
5. The blood treatment machine according to one of the preceding claims, wherein the optimum blood flow value (Qb_optimum) is determined in dependence on a new blood flow value (Q_b) or in dependence on the blood flow target value (Qb_target) according to a previously stored data table and is stored in the optimum blood flow value memory, if the determination unit determines a dialysis fluid parameter extreme during or after the waiting/delay time (tx), the new blood flow value (Q_b) corresponding to the blood flow that actually prevailed at the time of occurrence of the parameter extreme.
6. The blood treatment machine according to one of the preceding claims, wherein the control device (15) calculates the blood flow alteration rate in dependence on a predetermined blood flow start value (Qb_start), the blood flow target value (Qb_target) and a predetermined blood flow alteration period (t).
7. The blood treatment machine according to one of the preceding claims, wherein the control device (15) sets the predetermined blood flow start value (Qb_start) to 50ml/min, the blood flow target value (Qb_target) being stored as a default value in the control device (15), or read-in by a communication unit (16), or read-in from a patient data card or from a server.
8. The blood treatment machine according to claim 4, wherein the delay/extension unit determines the waiting/extension time (tx) in dependence on the blood flow alteration rate, the blood flow target value (Qb_target), a dialysis fluid flow (Qd) and parameters of the blood treatment machine, or reads-in the waiting/extension time (tx) from a previously stored data or value table in dependence on the delay time (Δt) between the actual occurrence of the dialysis fluid parameter extreme and its detection at a detection site, the delay time (Δt) and the blood flow target value (Qb_target) being stored in said value table as pairs of values in dependence on parameters of the blood treatment machine.
9. The blood treatment machine according to one of the preceding claims, wherein the blood flow target value (Qb_target) is predetermined via a communication unit (16).
10. The blood treatment machine according to one of the preceding claims, wherein altering of the blood flow alteration rate occurs through a blood pump control unit.

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